With Americans, it's bottoms, bottoms, bottoms. 'Get your ass out of the sling'; 'Let's get our asses into gear here, guys'; 'Okay, dudes, let's go kick ass', and so on. They need a euphemism. If every time they mentioned asses a Goatse (pronounced 'goat-see' and if you don't know what that is DO NOT GOOGLE IT because - really - you will be sorry) sprang to the American mind, they'd soon change their ways. Which would be a shame, particularly when it comes to the full, metaphorico-anatomically explicit version: not the ass but the asshole.

Before we continue, let's clarify one thing: an arsehole is not an asshole. My edition of S J Perelman's letters begins with a majestic declension of Yiddish insults, from the humble shlemiel to the malign and virulent paskudneh. Many of these - the klutz, the shmendrick, the shlemazl, the trombenik, just for starters - are subsets of the arsehole. But none of them are assholes. Perhaps they didn't even have assholes when Yiddish was evolving. Perhaps there wasn't the scope; perhaps they couldn't afford them. But whatever the reason, Yiddish, the greatest language in the world for carefully graduated ad hominem insults, contains no equivalent of the modern asshole.

In the 21st century, this is a shortcoming. As Aaron James's new theory of the asshole indicates, the breed is increasingly at large. What we see as the breakdown in social order - whether rude bastards shoving to the front of the queue or hair-gelled bankers in Thomas Pink shirts and impotence cars just not understanding why we want to break their spines - James, in part at least, attributes to the rise of the asshole.

The defining feature of the asshole, he suggests, is an 'entrenched sense of entitlement that immunizes him against the complaints of other people'. It's a moral failing - fundamentally different from the failings of the psychopath - because the asshole is

morally motivated ... The asshole takes himself to be justified in enjoying special advantages ... Given his sense of his special standing, he ... is resentful or indignant when he feels his rights are not respected, in much the same way a fully sociable, cooperative person is.

James's picture is persuasive. We are surrounded by assholes. Like obscenity, we know them when we see them. Rich people who think they are rich because they are special. Anyone who jumps the queue and shouts 'Fuck you' when remonstrated with. The morally bereft in Audis who believe themselves excused from normal courtesy, and indeed from the laws of physics as they apply to braking distances. (This last is often also found in lorry drivers, but I'd attribute that to type 2 diabetes and piles, rather than to a moral failing.)

Identifying them is easy. James fingers, among others, Donald Trump, Silvio Berlusconi, Simon Cowell and Mel Gibson. He claims, plausibly, that George W Bush wasn't an asshole, but was in thrall to a lot of them, most notably the asshole's asshole, Donald 'Asshole' Rumsfeld. The argument is readily extended. The current coalition government is mostly composed, not of assholes (with the surprising exception of Iain Duncan Smith), but of twats, amateurs and posh fuckwits. It may be a flaw in James's thesis that he lacks the experience of the Etonian asshole; but, equally, he lacks the counter-argument of royalty, the great advantage of which is that it guarantees that our nominal head of state may, as occasionally happens, be a tyrant, a shmuck or an idiot, but never an asshole because his or her supreme entitlement is constitutionally enshrined so need not ever be exerted.

Perhaps controversially, James also questions the belief that assholes are always men. Received opinion has it that a female who betrays asshole qualities is, by simple linguistic convention, referred to as a 'bitch'. Not so - he cites as an example the rabid right-wing 'commentator', the spittle-flecked horror Ann Coulter. The difference? 'The bitch betrays you behind your back. The asshole fails to recognize [your justifiable complaints] to your face.'

The thrust of James's thesis is timely. We live under what he terms asshole capitalism: a proposition with which few would argue. The entitlement, the deafness, the ruinous depradations of the group we refer to, in shorthand, as 'the bankers' are all too visible; the annulment of Fred Goodwin's knighthood is only one tiny cough of disapproval, and I bet Goodwin, in his inner asshole, feels affronted and hard done by.

It's not new, and it's not confined to the powerful. James was moved to draw up his theory by the sight of asshole surfers who screw things up for everyone else because they feel entitled to. And the Romans had no shortage of assholes, as anyone who has read Juvenal, Martial, Petronius or Horace will know.

But is the asshole genuinely culpable, or is he sick? James argues powerfully for the former. On the other hand, ICD-10, the World Health Organisation classification of diseases, identifies 'dissocial personality disorder' (F60.2) as being diagnosed by any three out of six signs, including 'callous unconcern for the feelings of others', 'very low tolerance to frustration', 'behaviour ... not readily modifiable by experience' and the tendency to offer 'plausible rationalisations for the behaviour bringing the patient into conflict with society'. Perhaps, on the other hand, there's no reason why one can't be mad and still an asshole, still morally culpable.

The trouble with this energetically argued and provoking thesis is simply the word 'asshole'. It's hard for an Englishman to forget the origins - however euphemised and transformed - of the word. One keeps seeing bottoms. But it's well worth the discomfort; not least for Aaron James's magnificent 'Letter to an Asshole', which ends the book. 'It pains me', he writes, 'to tell you that ... many who know you will find your death relieving. There will be a quiet celebration.'

At which point, I imagine, many readers will uncap their pen and begin to draw up their own list. Who's top of yours?